A Double-Blind, Randomized Comparison of Aztreonam Plus Clindamycin with Tobramycin Plus Clindamycin in Abdominal Infections.

Seventy patients with intraabdominal infections were randomly assigned in double-blinded fashion to receive either the combination of tobramycin plus clindamycin (TM/C) or aztreonam plus clindamycin (AZ/C). Thirty-four patients received AZ/C and 36 were given TM/C. Average ages were 62 years (TM/C) and 66 years (AZ/C). In approximately one-half of both groups, the source of infection was perforated colon or perforated appendix. There were no significant differences in demographic factors between these groups, although those given AZ/C had a more serious long-term prognosis due to underlying diseases. The average lengths of treatment were 10 days (TM/C) and 9 days (AZ/C). Clinical response to therapy did not differ, as 84% of the TM/C patients and 78% of the AZ/C patients had satisfactory clinical responses. The two regimens differed in adverse effects, as an elevated PT/PTT was more frequently (p < 0.05) observed in AZ/C. All PT/PTT elevations responded to injections of vitamin K, and no serious bleeding occurred. Choice between these regimens depends on differences in cost and the risk of adverse effects, as both regimens appear equally effective for treatment of abdominal infections in conjunction with appropriate surgical intervention.